Study on SPF/DB Technology for Two-Sheet Hollow Structure of 1420 Al-Li Alloy

The two-sheet hollow structure of the 1420 Al-Li alloy was prepared by the method of superplastic forming and diffusion bonding. The interface combination status of the diffusion bonding region and the microstructure of the superplastic forming region were observed by an optical microscope. The thickness distribution of the superplastic forming region was measured by an ultrasonic thickness meter machine, the defect detection was tested by X-ray nondestructive inspection, and the failure modes of the samples were analyzed. The results showed that the two-sheet hollow structure of the 1420 Al-Li alloy was prepared successfully, the structure was integrated, and there were no shape defects such as pit, wrinkle, and collapse. The structure shape was almost attached to the die completely, and the thickness was almost uniform distribution. The no deforming area of the two-sheet hollow structure of the 1420 Al-Li alloy was a long strip, rolled microstructure, while the grains near the round corner area were equiaxed states resulting from dynamic recrystallization. The improper control of the superplastic gas pressure in the forming process would lead to the tearing or the die-attaching failure for the two-sheet hollow structure of the 1420 Al-Li alloy.